The present invention relates to a manufacturing method of a semiconductor device and can be used favorably for a manufacturing method of a semiconductor device including a solid-state image sensing device for example.
As a solid-state image sensing device, a solid-state image sensing device (CMOS image sensor) using a CMOS (Complementary Metal Oxide Semiconductor) has been developed. The CMOS image sensor is configured so as to include a plurality of pixels having photodiodes and transfer transistors.
In Japanese Unexamined Patent Application Publication No. 2005-142319 (Patent Literature 1), a technology of removing a metallic pollutant attaching to the bottom face of a trench is disclosed. According to the abstract, the temperature of a substrate is controlled to 200° C. to 600° C., excitation energy is given by plasma, and thus oxidation reaction is caused on the surface of a silicon film. As a result, a silicon oxide film is formed over the surface of the silicon film exposed in a trench. A metallic pollutant coheres at the interface between the silicon oxide film and the silicon film and comes to be metallic silicide. The silicon oxide film is removed by an HF system solution. In accordance with this, the metallic silicide is also removed.
In Japanese Unexamined Patent Application Publication No. 2008-60383 (Patent Literature 2), a technology that makes it possible to form a gate insulating film having a high reliability is disclosed. According to the abstract, after a groove is formed over the surface of a silicon substrate, the inner surface of the groove is cleaned to remove pollutants and successively a defective layer over the inner surface of the groove is removed by isotropic etching using a radical generated by ionizing a fluorine-contained gas and an oxygen gas at a substrate temperature of 200° C. or lower.
In Japanese Unexamined Patent Application Publication No. 2006-59842 (Patent Literature 3), a technology of inhibiting stress caused in a substrate by an element isolation (STI) section and mitigating the problem of joint leak current is disclosed. According to Example 3, a damaged layer formed inside a groove when the groove is formed in a silicon substrate by anisotropic dry etching is removed by isotropic etching.